textproduct: Quad Cities

KEY MESSAGES

- An upper low over the northern plains will continue to roll through the area through Tuesday morning, with mostly light amounts of rain and drizzle. Then expected a precip break for Wednesday thru Friday.

- Pleasant early fall weather is expected for Wednesday through Friday.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 132 PM CDT Mon Sep 21 2026

Though we remain cut off from significant moisture transport under a small upper low over the Midwest, our area is in a convergent low level flow near the Mississippi River to convergent flow just aloft a bit northwest around northeast Iowa. The upper low aloft is bringing lift to the northeast Iowa area, and will combine with both mechanisms over eastern Iowa and far western Illinois tonight into early Tuesday. The result, wet weather continues!

I have increased pops to 80+ percent over eastern Iowa this afternoon and tonight, mainly north of Highway 34, as the efficient process of lifting the saturated low level air mass continues. So far today, this is resulting in a hundredth or two per hour in this band, but over northeast Iowa, the deeper moisture has allowed slow moving showers to bring 0.36" to Waterloo this morning. I fully expect there to be some spotty county sized spots that receive 0.25 to 0.50 tonight, and up to an inch is possible in a worse case scenario, which is concerning, but we'd be unlucky to have the one or two small areas like that line up over a metro area. We'll just have to keep an eye on it, and also know the rate per hour is not expected to exceed 0.20 per hour. An isolated brief flash of lightning remains possible within the heaviest showers tonight.

Tuesday, the upper low is expected to weaken and move east, with drier air aloft gradually mixing in from the north. I expect clouds to linger (along with some rain/drizzle) through mid morning, followed by clouds and eventually some breaks by afternoon in the north. The dry hours in the afternoon should be able to allow for temperatures to rise to the mid 60s central and south, but the north should remain cool near 60.

The dry air will continue to arrive Tuesday night, with lows in the mid 40s northwest to low 50s southeast, under clearing skies. For now, fog may be held off by north winds at 5 to 10 mph, but that will need to be watched in this forecast.

Wednesday stands out as a very pleasant day, with highs in the mid 60s north to upper 60s central and south, as a brief period of upper ridging moves through the region. skies appear mostly sunny much of the day.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Issued at 132 PM CDT Mon Sep 21 2026

Thursday through Friday...Ensemble and upper jet trends suggest that the local area to benefit from becoming under the influence of some of the ridging of the blocked pattern aloft, which would lead to some fine fair weather fall days with highs in the 60s to near 70 and overnight lows in the 50s and 40s. Will have to watch for some upper trof energy to try and undercut the ridging and shuttle some showers or way Thu or into Friday, but the latest ensembles suggest an omega ridge to get pumped up along the MS RVR Valley from subsidence off developing east coast deep cyclone and erode precip as it tries to near the area from the west Thursday and especially on Friday.

Saturday and Sunday...Getting into a more uncertain period, but the same ensembles suggest another ridge-undercutting trof may finally bring in some shower chances to the area Sat into early Sunday. Currently temps look seasonable for the weekend.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1216 PM CDT Mon Sep 21 2026

Low clouds remain widespread over the area late this morning, and will continue to remain in these clouds through the period as northeast low level flow combines with a weak upper low over the area to bring widespread cigs around 800 to 1500 ft, drizzle, and rain. Tonight, a thunderstorm is possible, but that threat is low, compared to rain, which may be widespread over the entire area tonight and overnight as the upper low moves overhead. Current indications suggest this low aloft will move east of the area between 12Z and 15Z Tuesday. Behind the low, the moist atmosphere will slowly see improvement through the day Tuesday, but the morning is expected to be MVFR with high confidence.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.